[jira] [Commented] (KYLIN-2079) add explicit configuration knob for coprocessor timeout

["liyang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KYLIN-2079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15586995#comment-15586995 ] 

liyang commented on KYLIN-2079:
-------------------------------

Super busy recently. Sorry for the delay. Mahong shall respond.

> add explicit configuration knob for coprocessor timeout
> -------------------------------------------------------
>
>                 Key: KYLIN-2079
>                 URL: https://issues.apache.org/jira/browse/KYLIN-2079
>             Project: Kylin
>          Issue Type: Sub-task
>          Components: Storage - HBase
>    Affects Versions: v1.5.4.1
>            Reporter: Dayue Gao
>            Assignee: Dayue Gao
>             Fix For: v1.6.0
>
>         Attachments: KYLIN-2079.patch
>
>
> Current self-termination timeout for CubeVisitService is calculated as the product of three parameters:
> * hbase.rpc.timeout
> * hbase.client.retries.number (hardcode to 5)
> * kylin.query.cube.visit.timeout.times
> It has a few problems:
> # due to this timeout being longer than hbase.rpc.timeout, user sees "Error in coprocessor" instead of more descriptive GTScanSelfTerminatedException. moreover, the request (probably a bad query) will be retried 5 times, increasing pressure on regionserver
> # it's not intuitive to set coprocessor timeout by adjusting kylin.query.cube.visit.timeout.times
> I propose the following changes:
> # add a new kylin configuration "kylin.query.coprocessor.timeout.seconds" to explicitly set coprocessor timeout. It defaults to 0, which means no value, use hbase.rpc.timeout x 0.9 instead. When user sets it to a positive number, kylin will use min(hbase.rpc.timeout x 0.9, kylin.query.coprocessor.timeout.seconds) as coprocessor timeout
> # remove "kylin.query.cube.visit.timeout.times". For cube visit timeout (ExpectedSizeIterator), it's really a last resort, in case coprocessor didn't terminate itself. I don't see too much needs for user to control it, set it to coprocessor timeout x 10 should be a large enough.



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